Located in the Province of Rome. The city of Veroli (Verulae) is situated on the crest of the Hernican Mountains, at the elevation of 1640 feet above the sea level, with the River Cora running beneath it. Its antiquity is evidenced by the remains of Pelargic walls. Upon the loftiest portion stand the ruins of a very ancient castle which served as a prison for John X. The textile industry, which still flourished in the middle of the nineteenth century, is now reduced to very small portions. The cathedral and episcopal palace received their present form from Bishop Ennio Filonardi in the beginning of the sixteenth century. Some very precious manuscripts and documents are preserved in the archives of the chapter, among them the Breviary of St. Louis, Bishop of Tolosa. Adjoining the cathedral is the Church of St. Salome, whose body is believed to be preserved there. S. Erasmo still retains its Gothic porch, though its interior has been entirely transformed. The seminary has a rich library, the gift of Bishop Vittorio Giovardi, who had the seminary rebuilt in 1753. At the same period a school of canon and civil law, founded as early as 1538, was combined with the seminary.

Veroli was a city of the Hernici, and thus was allied with the Romans against the Volsei; remaining so during the Samnite War, it was able to preserve its autonomy. In 872 it was taken by the Saracens. In 1144 Roger I besieged it in vain. It served as a place of retreat for Alexander III and other popes. A memorable event in its history was the meeting which took place there between Honorius III and Frederick II. The humanists Giovanni Sulpizio and Aonio Palcario (Antonio Pagliari), the latter burned in 1570 for his writings in support of Protestantism, were natives of Veroli. The city boasts of having received the light of the Gospel from St. Mary Salome, whose relics, it is said, were discovered in 1209 through a vision sen by one Thomas. Nevertheless, no bishop is known before Martinus (743). The martyrs Blasius and Demetrius are still venerated there. Among the bishops worthy of mention are Agostino (1106) and Faramondo (1160), who had been abbots of Casamari; Giovanni (1223), the restorer of clerical discipline; Ennio Filonardi (1503), who was distinguished in the nunciature; Gerolamo Asteo (1608) a Conventual, founder of the seminary and author of many works, mostly unpublished; Domenico de Zaulis (1690), who restored the cathedral and other churches; Antonio Rossi (1786), who, with his whole chapter, took the oath of allegiance to Napoleon.

The diocese is immediately subject to the Holy See. It has 37 parishes, with 7000 souls; 100 secular and 100 regular priests; 10 houses of male religious, 11 of sisters; 4 schools for boys, and 5 for girls.